CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Income tax expense	$ 0	$ 0	$ 6,841
Gain on sale of discontinued operations, tax	0	0	10,215
Net unrealized holding gains (losses) on available-for-sale securities, tax	64	(146)	1,473
Amortization and unrealized gain (loss) on interest rate agreements, tax	(6,782)	13,017	43,238
Net unrealized gains on commodity cash flow hedges, tax	$ 0	$ 0	$ 3,183

Other Comprehensive Income (Loss), Commodity, Contract, Derivatives Qualifying as Hedges, Tax

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Other Comprehensive Income (Loss), Interest Rate Contract, Derivatives Qualifying as Hedges, Tax

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Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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Amount of tax expense (benefit) on gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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